ABSTRACT Core B [The Liver Metastasis Resource Core (LMRC)] will supply human tissues and animal models to support the four Projects in studying interactions between the liver microenvironment and the metastatic tumor cells that colonize it. The Core will standardize operations across Projects through three functions: (1) Providing human tumor tissue and blood specimens, along with thorough pathological annotation; (2) Producing novel transgenic and orthotopic mouse models of liver metastasis and patient-derived xenografts (PDX) in mice using human metastatic tumor specimens; and (3) Analyzing mouse and human biomarkers, as well as isolating and characterizing circulating tumor cells (CTCs) and extracellular vesicles (EVs) using several approaches, including a suite of NanoVelcro Assays, an emerging nanotechnology platform. Core B will provide these resources under the aegis of well-coordinated and efficient central processes that maximize productivity and cost efficiency for the Program. The Core has the following specific aims: AIM 1. Procure and process human biospecimens, for appropriate distribution to investigators. AIM 2. Generate transgenic, orthotopic, and PDX mouse models of liver metastasis. AIM 3. Collect and characterize blood components, including CTCs and EVs. In summary, Core B will provide investigators with well-annotated tissue specimens, managed under harmonized operating procedures across all collection sites and Projects. The Core will house all resources and expertise, professional and technical, to generate physiologically relevant mouse models to support the Projects. Centralized pathologic, clinical and technical services will enhance communication of data and analytical insight across all Projects, supporting the Program's overall goals.